The present invention relates to a mechanism for controlling the flow of fluid from a source of fluid under pressure to fluid actuatable devices. More particularly, the present invention relates to a mechanism for controlling the cooling of internal combustion engines, particularly vehicular diesel engines.
As is well known in the art, diesel engines operate best within prescribed elevated temperature limits. Both overheating and under-cooling such engines in undesirable for optimum operation.
In the past, one method of effecting appropriate cooling of such engines has been the use of shutters placed in front of the radiators servicing the engine. See, for example, U.S. Pat. No. 3,046,619. Upon reaching the upper limit of the optimum operating temperature range, the shutters are opened in response to thermostatically operated control valves, thereby exposing the radiator to ram air from the outside. Conversely, upon the engine temperature reaching the appropriate lower temperature, the thermostatically operated control valve actuates the shutter to close the communication of the radiator with cooling air. See U.S. Pat. No. 3,955,760 for an example of one such control valve.
Another type of device for controlling the cooling of such engines are fan clutches. In such devices the fan is activated and deactivated in response to a thermostatically operated valve mechanism. Illustrative of such devices is that shown in U.S. Pat. No. 3,253,687.
It has also been suggested to use both types of cooling devices; i.e., both shutters and fan clutches for effecting the cooling of such engines. One such device is described in U.S. Pat. No. 3,226,025. However, the control mechanism of the latter patent actuates the two devices by electrical means which are relatively complicated and therefore prone to failure in operation.
It is an object of the present invention to provide a dual action thermostatic control mechanism which will operate both a fan clutch and a shutter from a single relatively simple control mechanism which will not allow the fan clutch to operate with the shutter closed.